Raman, Rayleigh and Thomson scattering play roles in various detection techniques. One of the advantages of these types of scattering is that the signals are produced only during the illumination time, so no quenching effects are present and time gating of the scattered light provides a method for discrimination.
However, the challenge for hyperspectral imaging is that all the Raman, Rayleigh and Thomson scattering is generated at the same time, so distinguishing the various spectral components generally requires a spectrometer. This is particularly difficult for rotational Raman scattering, for which the spectra from all the Raman active species are intermingled, and where the pump laser Rayleigh scattering dominates at low frequency shifts. Furthermore, the use of a spectrometer limits the imaging capability to one dimension and significantly reduces the light collection efficiency (etendue) due to the spectrometer f number (acceptance angle), diffraction grating losses and slit width requirements.
A method and system for highly selective imaging of Rayleigh, Raman and Thomson scattering features associated with gases, plasmas, liquids and solids is therefore useful and desirable.